Roasting furnace



May 28,1940.

ROASTING FURNACE Filgd Nov. 29, 1939 5 Sheets-Sheet 1 E. DE REY; 2,202,444"

E. DE REY 2,202,444

ROASTING FURNACE Filed Nov. 29, 1939 3 Sheets-Sheet 2' Fig.2.

May 2s,v 1940.

E. DE REY ROASTING FURNACE Filed Nov. :29, 19:59

3 Sheets-Sheet 3 $4 mm mm Q g) m z Patented May 28, 1940 PATENT orrice ROASTING FURNACE Emmanuel De Rey, Berchem (Antwerp) Belgium Application November 29, 1939, Serial No. 306,747 In Belgium January 3, 1939 14 Claims. (01. 266-) The present invention relatesto a roasting. or calcining furnace which is particularly adapted for the thermal treatment of sulphurous ores such as blende and pyrite.

This treatment is usually carried out in circular furnaces having superposed floors, provided centrally with a rotary vertical shaft carryin impeller arms which spread the ore and cause it to move down from one floor to the next, while til 1 the air and the combustion gases flow upwardly,

the requisite heat being supplied either solely by the combustion of the ore treated or, indirectly, by gases from an auxiliary furnace. The use of furnaces of 'the superposed floor type en- 15 tails inconveniences which are due, e. g., to the production by the falling ore of abundant dust the recovery of which requires costly de-dusting plants, and to the fact that'the metal shaft and impeller arms are continuously subjected to the action of corresive gases at high temperature,

whereby they are rapidly deteriorated.-

' It has also been proposed to use single floor furnaces, but theseare suitable neither for continuous operation, nor for the treatment of sufficiently large quantities of ore towarrant a commercial output.

The objects of the present invention are to obviate the inconveniences of these known furnaces and to provide a single floor furnace that is adapted for continuous operation and possesses impelling meansarranged outside the furnace, such means being actuated periodically to move the charge forward. The furnace according to myinvention comprises a series of interconnected chambers arranged zigzag-fashion on the. same level and provided with doors through which successive charges may be impelled fromone chamber to the next chamber.

The chambers are arranged at [15 to the longitudinal axis of the furnace and they are directed alternately to one side and to the other, each chamber thus extending in a direction at right angles to the preceding chamber and to the following chamber. Extending parallel to the longitudinal axis of the furnace are on' each side thereof tracks on which run trucks carrying a the impellers, one of' said impellers co-operating with all the chambers directed to one side and the other impeller co-operaxting with all the chambers directed to the other side of the furnace.

v Each impeller comprises rabbles carried by arms adapted to drive them horizontally into the 55 chamber in operation. Behind the rabbles is a shield which, when the door of the chamber is open, is adapted'to' close the door opening during the rabbling operation in order to avoid thermal losses.

The movement of therabble arms comprises a.

forward sliding motion to sweep the sole, a lifting motion and a backward sliding motion.

In order that the featuresof the furnace according to the invention maybe better understood-reference will be had to the accompanying 1b drawings which illustrate byway of example a constructional form of said furnace.

In the drawings:

Fig. '1 is a diagrammatic plan View of the furnace structure and of two impelling devices 15' adapted to'co operate therewith.

Figs. 2 and 3 are vertical cross-sections, on a larger scale, taken on lines IIII and III-III respectively of Fig. 1.

Figs. 4 and 5 are an elevation and a plan view 0 respectively "of an impeller device, also on a larger scale. 7 I

Figs. 6 and 7 are cross-sectional views of lines VI--VI and VIP-VII respectively of Fig. 4.

Fig.8 is a detail view on an enlarged scale. 5 As shown in Fig. 1 the furnace structure comprises a series of intercommunicating chambers I, '2, l 2 l Z arrangedat 45 to the longitudinal axis of the furnace and directed alternately to one side and to the other. At the 3 inlet end ofeach'chamber is an opening 3 closed by a door 4." 1 Q Extending parallel to the longitudinal axis of the furnace are on each side thereof tracks 5. and 6 on run a truck I and a truck 8 respectively. These-truckscarry each an impeller device having at their ends rabbles 9 carried by arms 50 extending obliquely with respect to the tracks 5 and 8. so that when one of said trucks is stationary in front of an opening 3, the rabbles can be pushed as far as the end of the chamber. I

Above thefirst chamber l is an ore container H (Fig. 2) from which an automatic distributor l2 delivers measured quantities of ore into telescopic hoppers it from which they are discharged onto the'sole of chamber I without dust production. The ore'then is spread along the sole by the rabble 9. In this chamber the ore begins to be heated by the gases which come from the opposite end of the furnace and escape through the chimneylt.

The doors llof the successive chambers are periodically lifted to]. permit of'gthe rabbles on truck I and on truck 'il' alternately pushing the charge from one chamber to the next until it reaches the last chamber 2" whence the roasted ore falls into silos l5 where it is collected.

In operation, the trucks 1 and 8 move stepwise along the furnace from or 2 respectively until chamber or 2 stopping at every chamber to move forward the charge therein.

The furnace illustrated by way of example is intended for roasting ores which are sufficiently rich in sulphur to keep up their combustion until the end of the roasting operation. Only last pairs of chambers H, 2 I 2 are heated externally by means of combustion gases from a small furnace l6 (Fig. 3) circulating in fines above and below the furnace. In the furnace itself, the gases evolving from the ore being roasted flow in contra-current to the direction of movement of the ore and they escape through the chimney I8 towards suitable recuperation apparatus (not shown).

The rabbles and their impeller means being normally situated outside the furnace, it is important that they should be operated without giving rise to an influx of outside air that might interfere with the roasting operation. To this end, the impeller devices are so constructed that they cause the door openings to be closed while rabbling takes place.

Fig. 4 shows a rabble carrying truck I in front of one of the doors 4 of the furnace. The door 4 being movable in upright slides l9 and balanced by a weight 20, is lifted by a cable 2| wound on a pulley 22 when said pulley is rotated by gears 23 under the action of a lever 24. This lever projects in the path of a striker 25 on the truck 1, so that it causes the door 4 to open automatically at the moment the rabble 9 is about to enter the furnace.

The rabble 9 preferably comprises a plurality of V-shaped teeth 59 having an inclined forward edge as shown in Fig. 8. The rabble teeth 59 are staggered and secured to cross bars carried by a pair of arms l0. Said arms it! are supported on rollers 69 (Fig. 6) and they have rearward extensions in the form of racks 26, which mesh with pinions 21 rotated from a motor 28 through suitable reducing gears 29 (Figs. 4 and 5).

Slidably mounted on the rabble arms I9 is a shield 30 adapted to close the opening 3 during the rabbling operation. The shield 30 is secured to a pair of arms 3| which are supported on rollers 32 (Fig. 6) and have rearward extensions in the form of racks 33 which mesh with pinions 34 rotated by a cable 35 passing over pulleys 36. Cable 35 carries a weight 31 which is guided in a standard 38 and tends to push the shield 30 forward, against a stop 39 carried by the arms I 0.

The shield carrying arms 3| also carry the striker 25. When the motor 28 is actuated for rabbling, the arms ID are moved longitudinally towards the furnace. Urged by the weight 31, the shield and arms 3| follow their movement and the striker 25 secured to the arms 3| strikes against the end of lever 24, causing the door 4 to be lifted as the rabble 9 arrives in front of it.

The shield 30 stops as it engages the opening 3 while the rabble enters the furnace and pushes the ore in front of it, spreading same up to the end of the chamber. During this movement the forward portion of the rabble arms ID are supported as cantilevers on rollers 40 the axes 4| of which are carried by the shield arms 3|.

When the rabble 9 has reached the end of its travel, it is slightly raised, then it is moved backwards by the motor 28. The movements described above are then repeated in reverse sequence, i. e., the stop 39 pushes back the shield 30 and the striker 25 leaving the arm 24 allows of the door 4 closing by its own weight.

In order to impart up and down movements to the rabble arms l0, said arms and the shield arms 3| are not directly mounted on the main frame 1 of the truck, but they are mounted in a structure 42 (Fig. 6) carried by an auxiliary frame 43 movably supported on the main frame 1. The frame 43 rests on rollers 44 (Figs. 4 and 6) carried by the lower ends of levers 45 mounted to rock on axes 46 in bearings 41 secured to the frame I. All the levers 45 are rocked in revision by a connecting rod 48 which is controlled from the extension 49 of one of said levers 45, said extension 49 being pivoted to a link 59 which in turn is pivoted at 5| to a wheel 52 rotated from a motor 53 through a reducing gear 54. During one revolution of wheel 52 the arms 45 are caused to perform in unison a'rocking motion that causes the frame 43 to be successively raised and lowered, said frame being guided by vertical ports 65 rigid with the frame I. The vertical motion of the frame 43 is so controlled that its upward movement coincides with the moment when rabble 9 is at its end of its travel. Suitable counterweights 55 are secured to the levers 45 to balance the weight of the movable frame 43.

As the shield 39 partakes in the upward movement of the frame 43, the sides of the opening 3 in which it is engaged at that time are so proportioned as to permit of this movement taking place. The size of the shield 3|! is such that the closure of the opening is ensured in the raised as well as in the lowered positions of the shield.

Since the arms l9 have to withstand high temperatures within the furnace, they are cooled by an inner air circulation.

To that end said arms are made hollow and are divided longitudinally into two conduits by a partition 56. A fan 5? blows air into one of said conduits, the air returning through the other conduit.

The motion of truck I along the track 5 is controlled by a motor 58 which drives the wheels 6| through pinions 62, shafts 63 and bevel gears 54.

Truck 8 is similar to truck 1, each truck 00- operating with the chamber on one side of the furnace, so that each successive charge is moved forward from chamber to chamber. All the chambers being on the same level, the ore is moved without falling and without producing .dust. The rabbles, at each operation, are only subjected to the heat in the furnace during the relatively short period required for rabbling one room, whereupon the rabble is withdrawn. Moreover, as the lifting of any door is immediately followed by the closing of the opening by the shield 39, the loss of heat is negligible.

The furnace described may of course be used for various operations, as for roasting, or drying or any kind of thermal treatment, and it will be understood that constructional modifications may be made therein and in the impeller means herein described without departing from the scope of the invention as defined by the following claims.

I claim:

1. In a roasting plant, the combination with a furnace structure comprising a succession of interconnected chambers arranged zigzag fashion at the same level, a door for each of said rooms, the doors of alternate rooms opening toone side of said structure and the doors of the other rooms opening to the other side of said structure, with impeller means on both sides of said structure for moving a charge of ore from any of said rooms to the next room.

2. In a roasting plant, the combination with a furnace structure comprising a series of inter- I spectively to operate in the chambers opening on their side of said structure.

. 3. In a roasting plant, the combination with-a furnace structure comprising a series of interconnected chambers arrariged zigzag fashion on a substantially horizontal level, said chambers being arranged at to. the longitudinal axis of said structure and opening alternately to one side and to the other side of said structure, of

tracks running parallel to said structure respectively on each side thereof, a truck on each of said tracks and an impeller on each of said trucks, one of said impellers being adapted to operate successively in the chambers opening'on one side of said structure, and the other of said impellers being adapted to operate successively in the chambers opening on the other side of said structure.

4. In a roasting plant, the combination with a 1 furnace structure comprising a series of interconnected chambers arranged zigzag fashion on a substantially horizontallevel, said chambers being arranged at 45 to the longitudinal axis of said structure and opening alternately to one side and to the other side of said structure, of doors for closing said chambers, a pair of impellers adapted to run each along one side of said struc ture, each of said impellers being adapted to cooperate with alternate chambers in said structure, means for operating said doors to allow of said impellers entering said chambers, and means on said impellers for closing said doors while said impellers are engaged in said chambers.

5. In a roasting plant, the combination with a furnace structure comprising a substantially horizontal series of interconnected chambers arranged zigzag fashion each at 45 to the longitudinal axis of said structure, said chambers opening alternately to one side and to the other side of said structure, of tracks running parallel to said structure respectivelyon each side thereof, impellers adapted to run each on one of said tracks, oneof said impellers being arrangedto move a charge of ore, from any chamber (I) opening on one side of said structure to an adjacent chamber (2); opening on the other side of said structure, and the other of said impellers being arranged to move a charge of one from any chamber (2) opening on the other side of said I structure to an adjacent chamber (I) opening on the first mentioned side of said structure.

6. In a roasting plant, the combination witha furnace structure comprising a substantially horizontal series of interconnected chambers arranged zigzag fashion each at 45 to the longitudinal axis of said structure, said chambers opening alternately to one side and to the other side of said structure, of doors for closing said chambers, an impeller movable along one side the rabbles are Withdrawn.

of said structure and adapted to enter successively the chambers opening on said side of structure, anotherjimpeller movable along the other side of said structure and adapted to enter successively the chambers opening on said other side of the structure, and means on said impellers for controlling the operation, of the doors of their respective'co-operating chambers,

' 7. In aroasting plant, the combination with a furnace structure comprising a substantially horizontal series of interconnected chambersarranged zigzag fashion each at 45 to the longitudinal axis of said structure," said" chambers opening alternately to one side and to the other side of said structure, of impellers adapted each to co-operate with alternate chambers in said structures, said impellers comprising rabbles, and means .for moving said rabbles horizontally into and out of said chambers.

'8. In a roasting plant according to claim 7, said impellers carrying each a shield adapted to close-the room in which the rabbles are operating, and means for withdrawing said'shield when .9. In a roasting plant according to claim '7, horizontal arms in each of said impellers carrying said rabbles, shields adapted to close said I chambers, horizontal arms in'each of said impellers carrying said shields, and means on said shield carrying arms for guiding and supporting said rabble arms. v

l 10. In a roasting plant according to claim 7, horizontal arms in each of said impellers carrying said rabbles, shields adapted to close said chambers, said shields being slidably mounted behindsaidrabblesand weights controlling the movements of said shields to cause them to follow said rabbles.

11. In a roasting plant according to claim 7, means for lifting said rabbles at the end of their 12. In a roasting plant, the combination with a furnace structure comprising a substantially horizontal series of interconnected chambers arranged zigzag fashion each at 45 to the longitudinal axis of said structure, said chamber opening alternately to one side and to the other side of said structure, of tracks running parallel to said structure respectively on each side thereof, a truck adapted to travel on each of said tracks,

a frame'on each of said trucks, an impeller of said frame, and means for rocking said levers in unison.

l4. Ina roasting plant according to claim 12,

doors for closing said chambers, slidesfor said doors, means for opening and closing said doors,

and shields on said impellers for closing said chambers when said doors are open, said shields being adapted to slide in the openings of said chambers. l

EMMANUEL DE REY.

outstroke and for lowering them at theend of] their instroke. 

